Translate

Friday, March 3, 2017

Are the Oceans’ Upper Layers
Really Acidifying?

Bad models, not measurements, have suggested ocean acidification in the upper layers of the oceans. As detailed in Part
1, NOAA’s Bednarsek, incorrectly attributed the dissolution of sea
butterfly shells to anthropogenic CO2 although the evidence clearly showed the
natural upwelling of deeper low pH waters were to blame. Based on models
employed by NOAA’s Feely and Sabine, Bednarsek claimed the upper ocean layers
are becoming more acidic and less hospitable to sea butterflies relative to
pre-industrial times. However detecting the location and the depth at which
anthropogenic CO2 now resides is a very, very difficult task. Because the ocean
contains a large reservoir of inorganic carbon, 50 times greater than the
atmospheric reservoir, the anthropogenic contribution is relatively small. Furthermore
anthropogenic carbon comprises less that 2% of the combined CO2 entering and
leaving the ocean surface each year. Thus there is a very small signal to noise
ratio prohibiting accurate detection of anthropogenic CO2. Despite admittedly
large uncertainties, modelers boldly attempt to infer which layers of the ocean
are acidifying.

Sea Butterfly Limacina helicina

(To clarifying terminology, an organic carbon molecule is a
molecule that is joined to one or more other carbons, such as carbohydrates and
hydrocarbons. CO2 with a lone carbon is considered inorganic, and
when dissolved can take 3 forms (or “species”) collectively referred to as Dissolved Inorganic Carbon (henceforth
DIC): 1) Carbonic acid (H2CO3),2) Bicarbonate ion (HCO3-)
after losing one H+ 3) Carbonate ion (CO3-2) after losing
a second H+ )

However model results are based on three very dubious
assumptions:

1) Models assume surface layers absorb anthropogenic CO2 by
reaching equilibrium with atmospheric concentrations. With minor adjustments,
models simply calculate how much dissolved inorganic carbon (DIC) will be added
to the ocean based on increased atmospheric CO2 since pre-industrial times.

2) Models assume CO2 will diffuse into the upper ocean
layers and be transported throughout the ocean in a similar fashion to tracers,
like CFCs. Because CFCs accumulate disproportionately near the surface, models
assume DIC does as well.

3) Models assume biosphere is in a steady state. Thus they
do not take into account increased primary production and the rapid export of
carbon to depth.

Although there is no doubt anthropogenic CO2 is taken up by
the oceans, assertions that ocean surface layers are acidifying are the results
of faulty model assumptions.

What Equilibrium?

CO2 equilibrium is rarely achieved between ocean and
atmosphere. Ocean surface pH and thus calcium carbonate saturation levels are
determined by the efficiency of the biological pump. In other words, when,
where, and how much CO2 enters the ocean surface, requires surface CO2
concentrations to be lower than atmospheric concentrations. That difference
depends on how much CO2 is fixed into organic carbon by photosynthesis and
subsequently exported it to depth, or how much CO2 is upwelling. Photosynthesis
indiscriminately draws down all CO2 molecules that have invaded surface waters either
via upwelling from depth or by diffusion from the atmosphere. Despite opposing
effects of mixing and diffusion, the biological pump maintains a strong
vertical gradient of high surface water pH and low DIC, with decreasing pH and
increasing DIC at greater depths. In regions where strong upwelling of DIC from
the deeper ocean overwhelms the ability of photosynthesizing organisms to
sequester carbon, surface pH drops and CO2 is outgassed to the atmosphere.
Several models estimate that without the biological pump, atmospheric CO2 would
increase by 200 to 300 ppm above current levels.

The efficiency of the biological pump determines to what
depths anthropogenic carbon will be transported. However NOAA’s
Sabine does not model the effects of the biological pump, oddly stating
“although ocean biology plays an integral role in the natural distribution of
carbon in the ocean, there is no conclusive
evidence that the ocean uptake and storage of anthropogenic carbon, thus far,
involve anything other than a chemical and physical response to rising
atmospheric CO2.”

Does Sabine truly believe the undeniable biological pump
discriminates between anthropogenic and natural carbon? Or does he believe that
there have been no changes in primary production and carbon export?As primary production increases, so
does the carbon export to depth. Annual primary production in the Arctic has increased
by 30% since 1998. We can infer primary production increased in the
Sargasso Sea based on a 61%
increase in mesoplankton between 1994 and 2006. North Atlantic
coccolithophores have increased
by 37% between 1990 and 2012.
And primary production and carbon export in the Peru
Current has dramatically increased since the end of the Little Ice Age. The
increasing trend in primary production and accompanying carbon export is potent
evidence supporting an alternative hypothesis that the biological pump has
sequestered increased invasions of anthropogenic CO2.

An examination of seasonal changes in surface CO2
concentration, illustrates how the biological pump determines when and how much
CO2 enters the ocean, and how much DIC accumulates near the surface. As
exemplified by the graph below from 2008 buoy data off the coast of Newport,
Oregon (Evans
2011), each spring photosynthesis lowers ocean surface CO2 to 200 ppm, far
below current atmospheric concentrations and much lower than what would be
expected from equilibrium with a pre-industrial atmosphere. Spring surface
waters are supersaturated, and any downwelling or mixing of these
supersaturated waters cannot acidify upwelled water or subsurface layers.
Furthermore the springtime draw down conclusively
removes any anthropogenic CO2 residing in sunlit waters. Furthermore
experiments show CO2 is often a limiting nutrient and added atmospheric CO2
stimulates photosynthesis. Microcosm
experiments found that when atmospheric CO2 was increased, the plankton
community consumed 39% more DIC.

Upwelling season begins in summer extending through fall. As
illustrated above, upwelling events rapidly raise surface concentrations of
CO2, reaching 1000 ppm. Physics dictates there can be no net diffusion from the
atmosphere into the ocean when the oceanic concentration is higher than
atmospheric, and thus there are virtually no anthropogenic additions during
upwelling season. Here any lowering of surface pH or calcium carbonate
saturation must be due to upwelling.

Finally during the winter, (not illustrated) surface waters
exhibited a steady CO2 concentration of 340 ppm. Although photosynthesis is
reduced, and winter mixing brings more subsurface carbon and nutrients to the
surface, the surface remains below equilibrium with the atmosphere. Although
surface concentrations are low enough to permit the invasion of atmospheric
CO2, the biological pump continues to export that carbon to depth so that
surface layers remain supersaturated all winter.

Diffusion of CO2 into the ocean is a slow process. It is
believed that it requires about 1 year for the oceans to equilibrate with an
atmospheric disturbance. But as spring arrives, increasing sunlight again
enhances photosynthesis, so whatever anthropogenic CO2 that may have invaded
the surface over the course of the year, is once again fully sequestered and
pumped to depth, lowering surface CO2 concentrations to 200 ppm. Bednarsek’s
claim that anthropogenic CO2 is acidifying the upwelled water along the Oregon
California Coast is once again not supported.

Tracers Do Not Correctly
Simulate Transport of Anthropogenic Carbon

Tracers like chlorofluorocarbons
(CFCs) are synthetic gases that are biologically inert. They were
introduced to the world during the 1920s primarily as a refrigerant. Climate
scientists have assumed the physical transport and accumulation of CFCs and increasing
anthropogenic carbon will be similar. Below in Figure 1, the red area just
south of Greenland designates an area that has accumulated the most CFCs. This
local concentration happens when high salinity Atlantic waters cool and carry
surface water and its dissolved gasses downward to the abyss forming North
Atlantic Deep Water. It is estimated that this downwelling has exported 18% of
all CFCs below 1000 meters; implying dissolved anthropogenic carbon has been
similarly exported and sequestered. However elsewhere CFCs accumulate
disproportionally in upper surface layers, so models assume dissolved
anthropogenic CO2 is likewise accumulating nearer the surface.

Both CFCs and CO2 are gases, and their solubility is similarly
modulated by temperature. Warm waters of the tropics absorb the least amount of
CFCs and CO2, as illustrated by the dark blue regions in Figure 1 from Willey 2004.
Thus equatorial waters feeding the California Undercurrent that upwell along
the west coast have likewise absorbed the least amounts of anthropogenic
carbon, if any. (The extremely low level of CO2 diffusion into the tropical
ocean plus the super saturation of tropical waters, casts great misgivings on
any claim that coral reefs have been significantly affected by anthropogenic
acidification.)

However, unlike inert CFCs, any CO2 entering sunlit waters
is quickly converted to heavy organic matter by photosynthesis. Although
dissolved CFCs and dissolved carbon are passively transported in the same
manner, particulate organic carbon (alive or dead) behaves very differently.
Particulate carbon rapidly sinks, removing carbon from the surface to depth in
ways CFC tracers fail to simulate. Examination
of the literature suggests “various methods and measurements have produced
estimates of sinking velocities for organic particles that span a huge range of
5 to 2700 meters per day, but that commonly lie between tens to a few hundred
of meters per day”. Low estimates are biased by suspended particles that are
averaged with sinking particles. Faster sinking rates are observed for pteropod
shells, foraminifera, diatoms, coccolithophorids, zooplankton carapaces and
feces aggregations, etc that are all capable of sinking 500 to 1000 meters per
day. These sinking rates are much too rapid to allow respired CO2 from their
decomposition to acidify either the source waters of upwelling such as along
the Oregon and California coast, or the surface waters

Earlier experiments had suggested single cells sank very
slowly at rates of only 1 meter per day and thus grossly underestimated carbon export.
However single-cell organisms will aggregate into clusters that increase their
sinking rates. Recent
studies revealed the “ubiquitous presence of healthy photosynthetic cells,
dominated by diatoms, down to 4,000 m.” Based on the length of time healthy photosynthesizing
cells remain viable in the dark, sinking rates are calculated to vary from 124
to 732 meters per day, consistent with a highly efficient biological pump.
Although NOAA's scientists have expressed concern that global warming will
reduce the efficiency of the biological pump by shifting the constituents of phytoplankton
communities to small, slow-sinking bacteria, new research
determined that bacteria also aggregate into clusters with rapid sinking rates
ranging from 440 to 660 meter per day.

Sequestration of carbon depends on sinking velocities and
how rapidly organic matter is decomposed. Sequestration varies in part due to
variations in the phytoplankton communities. Depths of 1000 meter are
considered to sequester carbon relatively permanently, as waters at those
depths do not recycle to the surface for 1000 years. Weber 2016 suggests
25% of the particulate organic matter sinks to 1000 meter depths in high
latitudes while only 5% reaches those depths at low latitudes. But long-term
sequestration does not require sinking to 1000 meter depths. Long-term
sequestration requires sinking below the pycnocline, a region where the density
changes rapidly. Dense waters are not easily raised above the pycnocline, so
vertical transport of nutrients and carbon is inhibited creating long-term sequestration.
Because the pycnocline varies across the globe, so do sequestration depths.

Below on the left is a map (a) from Weber 2016, estimating
to what depths particles must sink in order to be sequestered for 100 years.
Throughout most of the Pacific particles need only sink to depths ranging from
200 to 500 meters. In contrast the golden regions around the Gulf Stream, New
Zealand and southern Africa must sink to 900 meters.

The map on the right (b), estimates what proportion of
organic matter leaving the sunlit waters will be sequestered. The gold in the
Indian Ocean estimates 80% will reach the 100-year sequestration depth, while
60% will reach sequestration depths along the Oregon California Coast. Again
casting doubt on Bednarsek’s claims of more recently acidified upwelled waters
acidifying sea butterfly shells. Elsewhere in map “b”, 20% or less of the
exported carbon reaches sequestration depths.

Estimation of sequestration depths and proportion of carbon reaching sequestraton

The combination of sinking velocities and sequestration
depths suggests significant proportions of primary production will be
sequestered in a matter of days to weeks. This is consistent with the
maintenance of the vertical DIC and pH gradients detected throughout our
oceans. However it conflicts with claims by NOAA’s scientists.

Biased by CFC observations Sabine wrote, “Because
anthropogenic CO2 invades the ocean by gas exchange across the air-sea
interface, the highest concentrations of anthropogenic CO2 are found in
near-surface waters. Away from deep water formation regions, the time scales for mixing of near-surface
waters downward into the deep ocean can be centuries, and as of the
mid-1990s, the anthropogenic CO2 concentration in most of the deep ocean
remained below the detection limit for the delta C* technique.”

That NOAA scientists fail to incorporate the fact that particulate
carbon can be sequestered to harmless depths in a matter of days to weeks instead
of “centuries” appears to be the cause of their catastrophic beliefs about
ocean acidification. Furthermore because CFCs have accumulated near the surface
with only miniscule amounts in the deeper ocean, the tracer provides absolutely
no indication of how upwelling brings ancient DIC to the surface. So by relying
on a CFC tracer, their models will mistakenly assume that increased concentrations
of DIC near the surface must be due to accumulating anthropogenic carbon, and
not upwelled ancient carbon.

The Ocean’s Biosphere Steady
State?

Given a steady export percentage of primary productivity,
increasing amounts carbon will be exported in proportion to increasing
productivity. Thus it is reasonable to hypothesize that if marine productivity has
increased since the end of the Little Ice Age (LIA) aka pre-industrial times, that
increased production will have sequestered the increasing amounts of
anthropogenic carbon. Although there are only a few anoxic (depleted oxygen)
ocean basins, where organic sediments can be well preserved, those basins all
reveal that since the Little Ice Age, marine productivity and carbon export has
indeed increased as the oceans warmed.

Research from Chavez
2011 is illustrated below and demonstrates that during the LIA, marine
primary productivity (d) was low, but has increased by 2 to 3 fold over the
recent 150 years. Sediments reveal that fast sinking diatoms increased 10 fold at
the end of the LIA, but likely due to silica limitations, since 1920 diatom
flux to ocean sediments has been reduced to about a 2-fold increase over the
LIA. Nonetheless numerous studies find estimates of sedimentary
diatom abundance is representative of carbon export production in coastal upwelling
regions.

The increased primary production coincides with over a
hundred-fold increase in fish scales and bones (f). And consistent with the
need for increased nutrients to support increased primary production, proxy
evidence suggests a 2-fold increase in nutrients in the water column (c). Such
evidence is why researchers have suggested their observed decadal increases in
upwelled DIC and nutrients might be part of a much longer trend. Finally in
contrast to the global warming explanation for depleted ocean oxygen, the
decomposition of increased organic carbon provides a more likely explanation
for observations of decreased oxygen concentrations in the water column (a) and
sediments (b). Because primary production had doubled by 1900, long before
global warming or before anthropogenic CO2 had reach significant
concentrations, it is unlikely anthropogenic CO2 contributed to increased
upwelling, increased primary production or any other trends in this region

However increased primary production alone does not
guarantee that sinking particulate carbon is removing enough carbon to
counteract anthropogenic additions. However there are dynamics that suggest
this must be the case. First consider that an examination of the elements
constituting a phytoplankton community, there is a common ratio of 106 carbon
atoms detected for every 16 nitrogen atoms (aka a Redfield ratio). Given that
nitrogen typically limits photosynthetic production, if carbon and nitrogen are
upwelled in the same Redfield proportion, unless other dynamics cause an excess
of nitrogen, photosynthesis might only assimilate upwelled carbon but not enough
to account for all the additional anthropogenic carbon.

However calcifying organisms like pteropods,
coccolithophores and foraminifera export greater proportions of inorganic carbon
because their sinking calcium carbonate shells lack nitrogen. This can create an
excess of nitrogen relative to upwelled carbon in surface waters. Second
diazotrophs are organisms that convert atmospheric nitrogen into biologically
useful forms. Free-living diazotrophs like the cyanobacterium Trichodesmium,
can be so abundant their blooms are readily observed. (The blooms of one
species are primarily responsible for the coloration of the Red Sea.) Some
diazotrophs form symbiotic relationships with diatoms and coral.
So diazotrophs can cause an excess of nitrogen that allows photosynthesis to
assimilate both upwelled carbon and anthropogenic carbon. Furthermore as
discussed in Mackey
2015 (and references therein) “To date, almost
all studies suggest that N2 fixation will increase in response to
enhanced CO2.”

With all things considered, the evidence suggests
NOAA scientists have an upside down characterization of the ocean’s “steady
state.” There is no rigid rate of primary production and export that prevents
assimilating anthropogenic carbon and pumping it to depth. On the contrary the
combined dynamics of nitrogen fixation and the biological pump, suggest the
upper layers of the ocean have likely maintained a pH homeostasis, or a pH
steady state, at least since pre-industrial times. Increases in atmospheric
CO2, whether from natural upwelling or from anthropogenic sources, are most
likely assimilated quickly and exported to ocean depths where they are safely
sequestered for centuries and millennia. As also discussed in the article How
Gaia and Coral Reefs Regulate Ocean pH, claims that the upper ocean has
acidified since preindustrial times are not measurements, but merely results
from modeling a “dead” ocean and ignoring critical biological processes.

His understanding of climate change evolved as he sought to understand the causes of the declines in local bird populations that he had studied each summer as part of the Sierra Nevada Neotropical Migratory Bird Riparian Habitat Monitoring project. He soon discovered maximum temperatures in the Sierra Nevada had declined since the 30s (see graph) as observed at the nearby Tahoe City weather station that is part of the US Historical Climate Network. It became clear that the Sierra Nevada were not overheating despite publications blaming wildlife extinctions on global warming.

The most important factors affecting local climate change were the cycles of El Nino and the Pacific Decadal Oscillation as well as landscape changes that had greatly altered the regional microclimates. Believing the politics of global warming have been misguiding conservation efforts, Jim Steele wrote the book Landscapes & Cycles: An Environmentalist’s Journey to Climate Skepticism and initiated his website Landscapesandcycles.net. The lessons learned from his students helped shape his writing style, making the book's science lessons most enjoyable and easily grasped by science noviceshttp://www.sfsu.edu/~sierra/.